1. Field of the Invention
The present invention relates to a paper-feeding mechanism, and more particularly, to a paper-feeding mechanism with fewer components to reduce cost and increase precision.
2. Description of the Prior Art
When printing to paper with a fax machine, a printer, or a multi-function product, a paper-feeding mechanism is utilized for feeding paper one sheet at a time into machines so as to proceed to faxes, printouts, copies, and so on. Please refer to FIG. 1, FIG. 1 is a diagram of a paper-feeding mechanism 10 of the prior art. The paper-feeding mechanism 10 includes a paper tray 12 for positioning print media 14, such as paper or transparencies. The paper-feeding mechanism 10 further includes a burster 16 installed below the paper tray 12, a shaft 18, a pickup arm 20, and a pickup roller 22. Both ends of the shaft 18 are fixed to two lateral sides of the paper tray 12. The shaft 18 is sheathed into one end of the pickup arm 20. The other end of the pickup arm is connected to the pickup roller 22. The pickup arm 20 rotates around the shaft 18 according to a change of thickness of the print media 14 on the paper tray 12 so that the pickup roller 22 can press the upper surface of the print media 14 steady. The pickup roller 22 can apply a normal force on the print media 14 so as to provide a friction force to move the print media 14.
Please refer to FIG. 2 and FIG. 3. FIG. 2 is a lateral view of the paper-feeding mechanism 10 in a full-of-paper condition in the prior art. FIG. 3 is a lateral view of the paper-feeding mechanism 10 in an empty-of-paper condition in the prior art. The pickup roller 22 can press the upper surface of the print media 14 steady and apply a normal force to the print media 14 so as to provide a friction force for causing the print media 14 to move downward. The burster 16 blocks a bottom of the print media 14 so as to buckle the print media 14 so that the top print medium can be separated from other print media and fed out individually. As shown in FIG. 2 and FIG. 3, the torque generated by the shaft 18 not only drives the pickup roller 22 connected to the pickup arm 20 to rotate, but also drives the pickup arm 20 to rotate so that the pickup roller 22 can press the upper surface of the print media 14 and apply enough normal force to the print media 14. However, the power generated by a motor is transmitted to the shaft 18 via a chain of gears on the right side of the shaft 18, as shown in FIG. 1, and then transmitted to the pickup roller 22 from the shaft 18 via a chain of gears inside the pickup arm 20. There are too many components used in the paper-feeding mechanism 10, such as the shaft 18, the outer casing of the pickup arm 20, many idle gears, and the corresponding gear shafts, so that the cost and operating noise increase and precision decreases.